Carburetor



April 3, 1934. w, H. ASTON 1,953,384

CARBURETOR Filed March 31, 1952 Patented Apr. 3, 1934 UNITED STATES PATENT OFFICE 1 Application March 31,

1932, Serial No. 602,323

In Great Britain May 13, 1931 8 Claims.

This invention relates to improvements in carburetors and has for its object to provide a carburetor which will ensure the easy running and rapid acceleration of an internal combustion engine with which it is employed, and at the same time ensure a reduction in the consumption of fuel by the engine.

In particular the invention comprises a novel construction of carburetor embodying a narrow annular conical mixing chamber in combination with special air inlet port and fuel jet arrangements which will appear from the ensuing description and which are specifically set forth in the appended claims.

A construction of carburetor according to this invention which has, in practice, given excellent results will now be described with reference to the accompanying drawing in which:--

Figure 1 is an elevation of a carburetor constructed'in accordance with this invention,

Figure 2 is a vertical section'of the induction chamber 3 of the carburetor illustrated in Figure 1, but drawn to a larger scale,

Figure 3 is a vertical section at right angles to the section shown in Figure 2 and illustrating a modified form of choke hereinafter described,

Figure 4 is a plan view of the detached base of the mixing chamber of the carburetor, hereinafter described,

, Figure 5 is a view similar to the lower portion of Figure 3, but illustrating a modification of the invention, and

Figure 6 is a plan of the lower member illustrated in Figure 5.

Referring to Figures 1 to 4, the carburetor comprises a float chamber 1 arranged to supply fuel through a passage 1a provided in a member 2 connecting the float chamber to the lower end of an induction chamber 3 which incorporates a mixing chamber according to the invention as hereinafter described. The induction chamber 3 comprises a bottom plate 4 secured to the outer end of the member 2 by means of a hollow screw 4a arranged to extend through an opening formed in the outer end of the member 2, and to screw into the plate 4. A lower body member 5 is mounted upon the plate 4 to which it is secured by means of screws 6 and the said member 5 is provided with two slot-like air inlet ports '7 diametrically opposed to one another and between which an upwardly extending cone 8 is provided around which an annular recess 9 is formed and with which the air inlets 7 are arranged to communicate. The cone 8 is arranged to support five fuel jets of which one 10 is screwed vertically into the apex of the cone and the others 11 are screwed into the walls of the cone so as to extend transversely thereto and are equally spaced around the axis of the cone. The jets communicate with the underside of the cone 8 which with the plate 4 forms a chamber 12 into which petrol is fed from the float chamber 1. The normal petrol level is located at the bottom of the jets 11. 1

An upper body portion 13 which forms a cylindrical chamber 13a is secured to the lower portion 5 by means of screws 14 and a choke 15 is located within the chamber 13a and is secured in position therein by means of a screw 15a. The lower surface of the body portion 13' and of the choke 15 are formed with a somewhat steeper conicity than the cone 8, and thus forms a relatively narrow converging passage 16 therewith which is of annular conical configuration and constitutes the mixing chamber. A butterfly throttle valve 17 is pivotally mounted within the upper part of the body portion 13 and one edge of the valve, when it approaches the closed position, is arranged to be located adjacent to an orifree 18 in the wall of the chamber 13a which communicates with a passage 19 extending through the said wall and into a chamber 20 by means of a tube 20a, the lower end of which is located above a pilot jet 21. Air is supplied to the chamber 20 through a channel 22 under the control of an adjusting screw 23.

If desired, an auxiliary'air inlet may be provided by forming a port through the wall of the body member 13 which is arranged in register with a port formed through the wall of the choke 15 above the restricted portion thereof. Alternatively, the auxiliary air may be supplied by means of a ring of holes 24 formed through the wall of the choke 15, Figure 3', so as to communicate with an annular recess 25 formed in the periphery of the choke 15 and which is arranged in communication with the outer air through a passage 26 formed in the wall of the body member 13.

The upper end of the body member 13 is provided with a flange 27 to enable the carburetor to be secured to the induction pipe of an internal combustion engine.

A carburetor constructed in accordance with the above description and the drawing has given excellent results when used in conjunction with an A. E. C. Regent engine of a nominal horse power Royal Automobile Club rating of 37.2. and a maximum brake horse power of 95. The carburetor in question was similar to that illustrated in the drawing which is drawn to three-quarters full size, the choke being 1%; inches diameter bore at the restricted portion. In this particular case, the uppermost jet 10 was a No. 25 jet, whilst the four jets 11 were No. 35; the pilot jet 21 was drilled with a No. 78 drill. The ratio of the crosssectional area of the passage 16 at the base of the cone to the area at the apex thereof is preferably about 5 to 1.

With the engine and carburetor as specified, a marked increase in acceleration was obtained with an economy in fuel consumption of over 7 per cent, whilst the running of the engine was extremely smooth. I

It is to be understood that the jet 10 at the apex of the cone 8 may be dispensed with and the total area of the jets around the cone may be increased accordingly. Such an arrangement has been found advantageous for use in conjunction with petrol electric vehicles, that is to say, vehicles in which the internal combustion engine drives a dynamo and power is delivered to the road wheels by an electric motor driven by the current generated by the dynamo. This arrangement, whilst ensuring the requisite acceleration of the engine, effects a slight reduction in maximum power which, in certain circumstances, is desirable.

It is also to be understood that the cone 8 may be formed solid and the necessary passages provided therein for the supply of petrol to the jets from the chamber 12.

Instead of having two diametrically opposed air inlets, it will be appreciated that a continuous annular air inlet opening may be provided in the upper chamber so that air would be drawn in continuity from all points around the surface of the cone, and if a continuous slit is provided in the cone it will be appreciated that an unbroken stream of air will be drawn into contact with an unbroken annular jet of petrol issuing from the said slot.

It will be appreciated that the choke 15 may be arranged adjustable, so that during the operation of the carburetor the annular conical space forming the mixing chamber may be varied so as to enable the most beneficial working conditions to be obtained.

In the modification illustrated in Figures 5 and 6, two jets 11 are provided located diametrically opposite to one another upon the cone 8 each directly in the path of the" air current entering through one of the inlets 7, a jet 30, is provided which is located at the bottom of a vertical bore 31 formed centrally of the cone 8, the cone in this instance being formed solid, and passages 32 to the jets being formed therein for the supply of petrolto the jets. A series of air passages constituted by holes 33,'for example, six, inch in diameter are bored in the cone 8 so as to extend from the outer surface thereof through the cone and into the vertical bore 31 at a slight distance above thenormal petrol level which is slightly below the upper ends of the two jets 11 and above the upper end of the jet 30. The holes 33 may be upwardly inclined towards the bore 31 at about an angle of 30 to the horizontal, the holes being spaced from one another an equal distance around the cone.

In the modification of the invention described the total area of the three jets 11 and 32 is equal to the area of the five jets 10 and 11 described in the previous example, the jet'located'in the bore 31 of the cone, for example, being a N0, 65, whilst the two jets upon the exterior of the cone are each a No. 50. i

If desired, a compensating jet similar to the pilot jet 21 may be provided and a passage similar to the passage 19 arranged to extend from the compensating jet chamber to the interior of the upper part of the body portion 13 at a point below the valve 17. A suitable size of compensating jet for employment with the size of jets inthe mixing chamber as above described, is a Not 40 let.

What I claim is:-

1. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of the chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams and a fuel jet disposed in the path of each air stream transversely thereto, said jets projecting into the mixing chamber clear of the conical surfaces thereof and adapted to deliver fuel to the chamber from said reservoir.

2. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of the chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams, a fuel jet disposed in the path of each air stream transversely thereto and a pair of supplementary fuel jets located in said chamher one upon either side of the paths of said air streams, all said jets projecting into the mixing chamber clear of the conical surfaces thereof and being adapted to deliver fuel to the chamber from said reservoir.

3. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, the ratio of the cross-sectional area of thebase of said chamber to that of the apex being substantially 5: 1, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of the chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams and a fuel jet disposed in the path of each air stream transversely thereto, said jets projecting into the mixing chamber clear of the conical surfaces thereof and adapted to deliver fuel to the chamber from said reservoir.

4. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, the ratio of the cross-sectional area of the base of said chamber to that of the apex being substantially 5:1, a pair of opposed air inlet ports arranged in direct communicationwith the base of said chamber and each extending for substantially less than half the periphery of the chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams, a fuel jet disposed in the path of each air stream transversely thereto and a pair of supplementary fuel jets located in said chamber one upon either side of the paths of said air streams, all said jets projecting into the mixing chamber clear of the conical surfaces thereof and being adapted to deliver fuel to the chamber from said reservoir.

5. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of the chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams, a fuel jet disposed in the path of each air stream transversely thereto and projecting into said mixing chamber clear of the conical surfaces thereof and an additional fuel jet disposed at the apex of said chamber, all said jets being adapted to deliver fuel from said reservoir into said mixing chamber.

6. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, the ratio of the crosssectional area of the base of said chamber to that of the apex being substantially 5:1, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of said chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed and relatively inclined streams, a fuel jet disposed in the path of each air stream transversely thereto and projecting into said mixing chamber clear of the conical surfaces thereof, a pair of supplementary fuel jets located in said chamber one upon either side of the paths of said air streams and an additional jet located at the apex of said chamber, all said jets being adapted to deliver fuel to the chamber from said reservoir.

7. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of said chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed streams, a fuel jet disposed in the path of each air stream transversely thereto and projecting into said mixing chamber clear of the conical surfaces thereof, a vertical bore formed axially of the inner conical surface of said chamber, air passages communicating between the conical chamber and said bore and a fuel jet located at the bottom of said bore, said jets being adapted respectively to deliver fuel from said reservoir to said chamber and said bore.

8. In a carburetor the combination with a liquid fuel reservoir of a narrow annular conical mixing chamber formed between two similarly directed conical surfaces, the ratio of the crosssectional area of the base of said chamber to that of the apex being substantially 5:1, a pair of opposed air inlet ports arranged in direct communication with the base of said chamber and each extending for substantially less than half the periphery of said chamber, said ports being adapted to cause air entering therethrough to converge at the apex of said chamber as two mutually opposed streams, a fuel jet disposed in the path of each air stream transversely thereto and projecting into said mixing chamber clear of the conical surfaces thereof, a vertical bore formed axially of the inner conical surface of said chamber, air passages-communicating between the conical chamber and said bore and a fuel jet located at the bottom of said bore, said jets being adapted respectively to deliver fuel from said reservoir to said chamber and said bore.

WILLIAM HENRY ASTON. 

